Reduction of tailpipe emissions is a challenging goal in the automotive industry. As the acceptable values for tailpipe emissions continue to decrease, technologies must continually improve to meet the standards. Many efforts have been focused on reduction of hydrocarbon (HC) cold start emissions or emissions produced during the first several minutes after a vehicle is started. The traditional approaches to reducing cold start HC emissions include development of catalysts capable of warming up quickly and lighting-off at lower temperatures as well as optimizing engine cold start conditions to deliver heat to the catalyst as quickly as possible. However, even with very fast catalyst light-off, there are generally at least tens of seconds during cold start when the catalyst is not warm enough to convert any HC species. As a result, tailpipe emissions include unconverted HC species.